Add UCVolumeTool for reading files from UC Volumes

[jennsun]

support reading file from volume given volume name/path

mirroring what we currently do with vector search retriever tool: https://docs.databricks.com/aws/en/generative-ai/agent-framework/unstructured-retrieval-tools

See this notebook testing this uc volume tool and creating agent that can call tool reading from uc volumes: https://eng-ml-agent-platform.staging.cloud.databricks.com/editor/notebooks/3245073120416479?o=2850744067564480

example code snippet
langchain

from databricks_langchain import UCVolumeTool, ChatDatabricks

# Initialize the UC Volume tool.
vol_tool = UCVolumeTool(
    volume_name="catalog.schema.my_volume",
    tool_name="volume_reader",
    tool_description="Reads files from the project documents volume."
)

# Read a file from the volume locally for testing
vol_tool.invoke("reports/q4_summary.txt")

# Bind the volume tool to your LangChain LLM of choice
llm = ChatDatabricks(endpoint="databricks-claude-sonnet-4-5")
llm_with_tools = llm.bind_tools([vol_tool])

# Chat with your LLM to test the tool calling functionality
llm_with_tools.invoke("Read reports/q4_summary.txt and summarize it.")

openai:

import json
from databricks_openai import UCVolumeTool

# Initialize the UC Volume tool.
vol_tool = UCVolumeTool(
    volume_name="catalog.schema.my_volume",
    tool_name="volume_reader",
    tool_description="Reads files from the project documents volume."
)

# Read a file from the volume locally for testing
vol_tool.execute(file_path="reports/q4_summary.txt")

# Pass the tool to the OpenAI SDK
from openai import OpenAI
client = OpenAI()

response = client.chat.completions.create(
    model="gpt-4o",
    messages=[{"role": "user", "content": "Read reports/q4_summary.txt and summarize it."}],
    tools=[vol_tool.tool],
)

[jennsun]

note: unlike the vector search retriever tool which is a mlflow resource type

uc volumes are not and hence we will not add resource field here: https://www.mlflow.org/docs/latest/api_reference/_modules/mlflow/models/resources.html

[jennsun]

After some discussion we decided the best path forward here would be to add code snippet examples to read from UCVolume in our unstructured data docs instead of creating a separate local UCVolumeTool - we may want to move towards suggesting KA for uc volume search/retrieval in the long run. Created a separate emu pr to update docs with examples